This invention relates to a sheet capable of controlling the amount of passage of a fluid such as wind, earth, water (including sea water) or their mixture, more concretely, to a sheet suitable for a wind preventing sheet for reducing the velocity of the wind, a snow preventing sheet for reducing the amount of blown in snow, an earth and sand preventing sheet for reducing the amount of washed away earth and sand or invasion thereof, or a bird preventing or an animal preventing sheet.
Heretofore, a curing sheet, etc., have been usually used as a wind preventing sheet. However, although these sheet are excellent only in the function of preventing the blowing in wind, they can not control the amount of wind and also have a defect in their limited uses and executed areas, since the sheets themselves are heavy and in addition, when they fill wind by receiving wind, an excessive tension is imposed on mounted parts thereof.
While in the case of using a mesh sheet obtained by performing a resin treatment on a mesh cloth as disclosed in Japanese Unexamined Patent Publication 8-170244, although the executed area can be extended, the function of preventing the blowing wind and strength thereof are inferior, and there is still a problem that it can not be used in an occasion such as in the cases of the field sports which are apt to be affected by an air stream, since the wind passed through the mesh becomes a turbulent flow, even if the desired wind preventing function is obtained by optimizing the ratio of vacant spaces of the mesh,
For Example, in the case of controlling the wind surrounding a jumping stand in a skiing ground, the curing sheet can not be used since an executed area becomes wide and an excessive tension is imposed on the mounted parts thereof, and also obstructs the sights of spectators and judges. While by using the mesh sheet, it is difficult to control the wind velocity necessary for performing a jumping competition (less than 3 m/sec), and even if it can control the wind velocity, there are problems that the wind passing through the mesh becomes the turbulent flow to affect the competition and also strength thereof is weak and endurance thereof is inferior.
The object of this invention is to solve the problems of the above mentioned conventional technologies, and provide a sheet capable of controlling the amount of passage of a fluid consisting of, to begin with wind, earth, water (including sea water) or their mixture, excellent in visibility of the sheet and endurance, also flexible and having a good working efficiency, more concretely, a sheet suitable for a wind preventing sheet for reducing the velocity of the wind, a snow preventing sheet for reducing the amount of blown in snow, an earth and sand preventing sheet for reducing the amount of washed away earth and sand or invasion thereof, or a bird preventing or an animal preventing sheet.
As a result of research in order to accomplish the above object and carried out by the present inventor, it was found out that when spacings among groups of fibers arranged on a sheet having mesh state vacant spaces are controlled in a specific range, the desired sheet is obtained.
That is, by this invention, a sheet capable of controlling the amount of passage of a fluid is characterized in that the sheet is provided by arranging fiber groups A formed with slit state vacant spaces having a spacing of 0.5 mm or larger between adjacent fibers each other and fiber groups B as a lattice state, and containing a woven or knitted structure having mesh state vacant spaces having widths of each 2 to 15 cm and enclosed by the above fiber groups A and fiber groups B in an orientation direction of the fiber group A and in an orientation direction of the fiber group B.